By 'damning' I assume you are referring to the particular finding that there was no evidence of significant connections between Sadaam and al Qaeda - that there was no evidence of collaboration relevant to 9-11. And I also assume you use the term 'damning' because it reflects badly upon the administration's truth-quotient. It does.
First, let's recall that:
1) the White House did not want this investigation and sought to stop it.
2) it put up substantial roadblocks and frequently stonewalled commission requests (for information and interviewees), which the head of the commission, a Republican made frequent mention of while trying to do his assigned task.
More important than the above, recall that the mandate given the commission was limited to intel and response failures, and that the commission was limited to those questions and was disallowed from investigating whether the administration had 'cooked' the intelligence so as to facilitate war.
Let's also note that both Bush and Cheney have reiterated the rather weasely "we said there connections because there were connections", skipping conveniently over the commission's findings that those 'connections' were of no consequence to 9-11.
And finally, this is what Bush said yesterday...
"This administration never said that the 9/11 attacks were orchestrated between Saddam and Al Qaeda."
and then let's look at the wording from Bush's letter to the Speaker of the House and the President of the Senate seeking their backing for the war...
(2) acting pursuant to the Constitution and Public Law 107-243 is consistent with the United States and other countries continuing to take the necessary actions against international terrorists and terrorist organizations, including those nations, organizations, or persons who planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001.
Recall also that from the onset of administration talk of going after Sadaam, intelligence and state department voices (not to mention those from weapons inspectors and other nations' intel people) spoke out that it was al Qaeda and not Iraq which the evidence suggested was the proper target (Richard Clarke talks about this in his book, but there's much else as well, and even much here on the first or second iteration of our own US UN and Iraq thread).
Recall also that we know from Woodward and Clarke, amongst other evidence, that there was a push to go after Sadaam from Rumsfeld and others beginning sept 12. And there are the documents written and published as early as 92 by Wolfowitz and associates that Iraq ought to be a target of military action.
Chalabi, an associate of the Wolfowitz/Perle circle, submitted (it appears) false information to intel people, but much of this was questioned within the US agencies and within intel agencies elsewhere. Such voices were ignored, sidelined, or attacked as in the case of Valerie Plume's husband.
The administration saw what it wanted, misrepresented the quality and quantity of evidence, and did cook it up to make a deceitful case for this war. No other conclusion makes any sense at all, given all of the above. And they tried to scare citizens, with comments and suggestions like Rice talking of mushroom clouds.
The commission had access to all the information which the administration had before the war, and more, given the perspective of time and the accumulation of further evidence that time has allowed. The only other discernible difference is that claims made by Chalabi and friends was precisely testable once war had begun (recall Rumsfeld saying, "We know exactly which palm trees they (WOMD) are under".
The commission was independent and bipartisan, and even though the White House stonewalled and limited its scope of investigation in a manner
to disallow investigation of the most uncomfortable and embarrassing aspects of the whole enterprise, that commission's finding are 'damning'.
There are folks here on the site, you may or may not be one, who as yet believe that Bush and Cheney have been truthful as regards these matters, and that this commission have it wrong. If you are in that crowd, then I wish you the best. I'm not going to bother discussing these matters any further.